This application claims benefit of Japanese Application No.2000-273793 filed in Japan on Sep. 8, 2000, the contents of which are incorporated by this reference.
1. Field of the Invention
The present invention relates to an endoscope that is sterilized with high pressure steam after it is used.
2. Description of the Related Art
Hitherto, there are widely used medical endoscopes capable of observing internal organs and the like in a body cavity by inserting a slender insertion section into the body cavity and executing various types of treatment and remedy using a therapeutic device inserted into a therapeutic device channel when necessary.
Endoscopes used in a medical field observe internal organs and the like by inserting an insertion section into a body cavity and execute various types of treatment and remedy using a therapeutic device inserted into the therapeutic device channel of the endoscopes.
When an endoscope and a therapeutic device which were used once are to be used on another patient, they must be washed and sterilized after the completion of checkup and treatment executed by means of them to prevent infection among patients through the endoscope and the therapeutic device.
Recently, autoclave sterilization (high pressure steam sterilization) is mainly used to disinfect and sterilize medical equipment because the autoclave sterilization permits the medical equipment to be used just after sterilization and its running cost is less expensive.
For example, when the endoscope disclosed in Japanese Patent Unexamined Publication No. 2-283346 is repeatedly subjected to thermal load in high temperature/high pressure steam sterilization, a resin member used as the outer sheath layer of an insertion section composed of a flexible tube section is softened. When a spiral tube disposed inside of the resin member is assembled to the insertion section in a diameter-reduced state, the spiral tube applies a force to the flexible tube section in a diameter increasing direction, whereby the outside diameter of the flexible tube section may be varied in the diameter increasing direction.
Further, when the resin member absorbs moisture and expands, the outside diameter of the insertion section may be varied thereby in the diameter increasing direction.
When the diameter of the insertion section is varied in the diameter increasing direction, a disadvantage arises in that the inserting property of the insertion section is deteriorated as compared with its initial state.
An object of the present invention is to provide an endoscope of which outside diameter of the insertion section is prevented from being increased by a thermal load caused in a high temperature/high pressure steam sterilization process and which is excellent in an insertion property.
Briefly, in an endoscope of the present invention having a feature in a flexible tube section constituting an insertion section, the flexible tube section includes a spiral tube formed by spirally winding a metal strip, a mesh-like tube covering the outside periphery of the spiral tube; and an outer sheath layer composed of resin for covering the outside of the mesh-like tube, wherein when the outer sheath layer is softened by being subjected to a thermal load caused in a high temperature/high pressure steam sterilization process, the outside diameter of the flexible tube section is the same as or smaller than the outside diameter thereof before it is subjected to the thermal load. With this arrangement, even if the insertion section is repeatedly subjected to thermal load caused in a high temperature/high pressure steam sterilization process, the excellent insertion property of the insertion section can be secured at all times without increasing the outside diameter thereof.